There's speculation the Astros ace was hampered by plantar fasciitis in his left foot, but on Wednesday, general manager Jeff Luhnow refuted that, saying Keuchel was diagnosed with a mild foot sprain in his end-of-year physical.

News of the injury came recently when Keuchel was seen in a walking boot and admitted he slipped and fell during the World Series parade. Though it's unclear if the incident aggravated the injury, Keuchel is expected to be ready by spring training.

The foot issue might explain Keuchel's numbers in the second half of the season. The 29-year-old pitched to a 9-0 record and 1.67 ERA in the first half despite missing just under a month with a neck injury, but slipped to a 4.24 ERA, 29 walks, and a 1.38 WHIP in his final 12 starts.

He bounced back in the postseason, performing to a 3.58 ERA with only eight walks and 32 strikeouts in five starts (two in the World Series). Keuchel is slated to become a free agent after the 2018 season.